Monterey Bay Aquarium Research Institute

The late nights and early days of the California grunion

Karen Martin, Ph.D.
Pepperdine University

Wednesday, June 30, 2004
Pacific Forum 3:00 p.m.

Photo by William Hootkins

The grunion Leuresthes tenuis occupies a unique place in California culture, providing the opportunity this summer for an unprecedented collaboration between scientists, the public, government agencies, aquaria, and environmental groups to engage in the greatest grunion hunt in over 50 years. The spectacular reproductive behavior of beach-spawning grunion is justifiably celebrated, and the early life history of these fish is equally remarkable. Spawning and incubation of grunion eggs occur fully out of water along the sandy beaches of the California coast. Eggs buried in damp sand become competent to hatch about 10 days, but hatching itself is delayed until the embryos are mechanically triggered to emerge by agitation in seawater. This interaction of life history and environment permits survival during terrestrial incubation and a rapid switch to aquatic life. Adaptations associated with beach spawning will be described for grunion adults, eggs, and embryos.

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